A prior semiconductor wafer container which contains semiconductor wafers of high additional value is so light that the wafers can be transported by air. More particularly, such a semiconductor wafer container is essentially required to have a pressure-proof air-tight construction which withstands large variation in atmospheric pressure so as to be prevented from inhaling fine dust which tends to damage circuits on the semiconductor wafers, by breath even when it is subject to variation in atmospheric pressure on the ground or high in the atmosphere. Accordingly, the prior semiconductor wafer container has larger thickness or is formed of a material which locally reinforces it so as to have the desired physical strength to withstand variations in atmospheric pressure. Thus, it will be noted that the prior semiconductor wafer container is required to have more material than one which is used only on the ground. This results in an increase in weight and in high cost of material and manufacture, which prevents transportation by air from being made at low cost.